1. Field of Invention
This invention relates to electrical switches and is particularly directed to motion-actuated switches for controlling electrical circuits.
2. Prior Art
Motion-activated switches are widely used to control electrical circuits in response to motion resulting from acceleration, vibration, seismic activity or numerous other causes. Such switches may trigger alarms, or may control the activation or deactivation of various types of equipment. Thus, for example, in the event of an earthquake, motion-activated switches can automatically sound an alarm, actuate solenoid valves to shut off gas lines, etc. Numerous types of motion-activated switches have been proposed heretofore. However, many of the prior art motion-activated switches have been limited in response to a particular type of motion, such as tilting but not longitudinal motion or vice versa. Other prior art motion-activated switches have been responsive only to relatively cross motion and cannot be triggered by subtle movements. Still other prior art motion-activated switches have been complex and expensive, have required considerable maintenance or have been bulky in size and weight. A search in the United States Patent Office has revealed the following references:
______________________________________ U.S. Pat. No. INVENTOR ISSUED ______________________________________ 5,136,126 C. D. Blair Aug. 4, 1992 5,027,105 T. A. Dailet et al Jun. 25, 1991 4,789,922 T. Cheshire Dec. 6, 1988 4,628,160 R. D. Canevari Dec. 9, 1986 ______________________________________
Each of these references is subject to the disadvantages discussed above. Thus, none of the prior art motion-activated switches has been entirely satisfactory.